Most motor vehicles, including those that are used for private and commercial use, have a number of visual displays such as gauges, indicators and signs, which are used to assist the driver when driving, or to warn or inform the driver of a particular operation of the vehicle. Such displays may be digital or analogue and are generally located on the dashboard or front windscreen of a vehicle.
In recent times, there has been a move toward vehicles that do not run solely on fuel combustion engines, such as hybrid electric vehicles and fully electrically powered vehicles. Hybrid electric vehicles are being developed to deliver a number of benefits including the reduction of carbon dioxide emissions and the reduction of the world fuel consumption by vehicle drivers and to reduce the energy consumed by a vehicle during its day to day running. With the rise of such new technologies, new displays are being devised to assist the driver of a vehicle in understanding the technologies and how the technologies are working to deliver the benefits mentioned above.
One way in which a hybrid vehicle functions to reduce fuel consumption and carbon dioxide emissions is by converting ‘waste’ energy during braking into electricity through a regenerative braking system.
A regenerative braking system commonly includes an electrical machine, an Inverter and a High Voltage (HV) Battery. The electrical machine converts electrical power to mechanical power and conversely mechanical power to electrical power. The Inverter is used for the conversion of AC/DC electrical power. The Inverter is a high voltage component which converts a direct current supplied by the HV Battery and provides an alternating current to power the electrical machine when the vehicle is operating in traction mode e.g. when the vehicle is being driven forward.
When operating in a regenerative braking mode, the electrical machine operates as a generator to supply an electrical load. The electrical load creates a braking torque that is transferred via a driveline. In this way, kinetic energy is transferred from the wheels of the vehicle through the drivetrain to the electrical machine, which in turn converts the kinetic energy into electrical energy. The Inverter converts the electrical AC power regenerated by the electrical machine into High Voltage electrical DC power which in turn is used to charge the HV Battery. At the same time, the resultant electrical machine torque produced by the electric energy generation slows down the vehicle.
In addition to facilitating the powering of the vehicle in terms of traction, the HV Battery is also used for other operations for example, charging a 12 V battery, or to power an air-conditioning system of a vehicle.
The amount of energy regenerated during regenerative braking is dependent on a number of factors relating to kinetic energy. The efficiencies of a driver's driving style can influence this for example, how often the driver brakes, how hard the driver brakes and for how long the driver brakes.
Drivers are able to adapt or optimise their driving style if they have appropriate dynamic feedback and information to guide the driver to fully utilise the vehicle operation and features. However, existing displays for such vehicles do not provide a usable real-term indicator of how energy being saved by the vehicle is beneficial to the driver. Existing data representation displayed on hybrid vehicles are not in a meaningful format that the user will be able to understand and associate with driving the vehicle in an economical manner.
It is an object of the present invention to provide a method and system for providing feedback to the driver of a hybrid or electric vehicle which substantially overcomes or mitigates at least some of the above-mentioned problems.